Heretofore, missile stability and control was normally accomplished through the use of fin actuators, canards and hot or cold gas thrusters. Many of the existing designs used high pressure gas stored in pressure bottles. Missiles and projectiles are designed for storage lives of from 10 to 20 years. Over the storage life the high pressure gases can escape from a pressure bottle. Since pressure may be in the 10,000 psi range, loss of pressurization presents a reliability problem. The subject invention eliminates the problem of pressure loss by activating a fluid in a liquid form and converting the liquid to a high pressure gas at the time it is needed.
Prior to the subject invention, methods were developed to provide high pressure gas which included storage of liquids that reacted violently to generate a gas, high pressure gas storage systems and hot gas generators.
The use of two or more liquids that react exothermally to produce a hot gas is well known. This technique is used in large rockets for propulsion purposes. This type of technique has not been used to power control systems. The liquids pose a danger if inadvertently spilled or exposed to each other. Therefore, this technique is not widely used in man-portable weapon systems.
The cold gas high pressure storage system commonly used in a steel pressure bottle must be overdesigned to permit it to withstand handling and rigorous missile qualification tests. The pressures normally used are between 9,000 and 11,000 psi. The bottles have a tendency to develop slow leaks especially with light gases such a helium. The pressurization loss cannot be detected and therefore a missile or projectile may be fired with no gas pressure to power the control system or the like.
To circumvent gas leakage problems, hot gas generators have been developed. These generators usually use propellant as a source of high pressure gas. The propellant is ignited normally by an electrically or impulse fired squib. The gases are generated by the burning of the propellant. This type of gas generator has three major flaws. First, once the propellant is ignited, it burns at a fixed rate requiring that the excess gas be dumped. Secondly, the gases are very hot and may be in the excess of 2,000.degree. Fahrenheit. This creates a problem with insulating the control system actuators and the other missile components from this temperature. Finally the gas is similar to that generated by burning rubber tires and usually dirty and possibly corrosive. The solid contaminants must be removed to avoid clogging up the gas passage ways and condensing out in the controller. This is less of a problem if the hot gases are used in an impulse or propulsive controller since the plumbing can be relative short.
In the following U.S. patents: U.S. Pat. No. 4,092,830 to Rilett; U.S. Pat. No. 4,149,388 to Schneider et al; U.S. Pat. No. 4,163,371 to Groninger; U.S. Pat. No. 4,219,725 to Groninger and U.S. Pat. No. 4,255,646 to Dragoy et al various types of portable cryogenic power systems and liquified gas vessels are described. None of these prior art gases provide the unique features and advantages of the subject high pressure gas supply system for use in conjunction with missile control systems.